From a2c0b05a8c00e2b8337275dd0fd8a3264d1d1b10 Mon Sep 17 00:00:00 2001 From: Ronald Wahl Date: Wed, 1 Nov 2023 18:14:31 +0100 Subject: [PATCH] serial: 8250: 8250_omap: Do not start RX DMA on THRI interrupt commit c6bb057418876cdfdd29a6f7b8cef54539ee8811 upstream. Starting RX DMA on THRI interrupt is too early because TX may not have finished yet. This change is inspired by commit 90b8596ac460 ("serial: 8250: Prevent starting up DMA Rx on THRI interrupt") and fixes DMA issues I had with an AM62 SoC that is using the 8250 OMAP variant. Cc: stable@vger.kernel.org Fixes: c26389f998a8 ("serial: 8250: 8250_omap: Add DMA support for UARTs on K3 SoCs") Signed-off-by: Ronald Wahl Reviewed-by: Vignesh Raghavendra Link: https://lore.kernel.org/r/20231101171431.16495-1-rwahl@gmx.de Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_omap.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index c7ab296..1122f37 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -1282,10 +1282,12 @@ static int omap_8250_dma_handle_irq(struct uart_port *port) status = serial_port_in(port, UART_LSR); - if (priv->habit & UART_HAS_EFR2) - am654_8250_handle_rx_dma(up, iir, status); - else - status = omap_8250_handle_rx_dma(up, iir, status); + if ((iir & 0x3f) != UART_IIR_THRI) { + if (priv->habit & UART_HAS_EFR2) + am654_8250_handle_rx_dma(up, iir, status); + else + status = omap_8250_handle_rx_dma(up, iir, status); + } serial8250_modem_status(up); if (status & UART_LSR_THRE && up->dma->tx_err) { -- 2.7.4